How to resolve Event ID 33002

Hello,

In the event log, I see:

Event Type:      Error
Event Source:      MSSQL$MICROSOFT##SSEE
Event Category:      (2)
Event ID:      33002
Computer:      CHINOOK
Description:
The description for Event ID ( 33002 ) in Source ( MSSQL$MICROSOFT##SSEE ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: table, dbo.backupset.

In SQL Mangement Studio, I right-click on the properties of any of the SharePoint database names, and I see the following error message box that says:

Cannot show requested dialog.
An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)
Access to table dbo.backupset is blocked because the signature is not valid. (Microsoft SQL Server, Error: 33002)

These are SharePoint 3.0 databases and I am using SQL Server 2005 Mangement Studio on Windows Server 2003. Can you explain why this error occurs and how I can fix them?

Thanks,